Problem and state coverage. A borrowed phone, a long drive with a guest, an overnight kid takeover. The user has no way to stop the shelf from logging without leaving the app or signing out. The Pause state machine surfaces the timer in every state: default, hover, press, paused, expiring, resumed, clock-skew error. The timer is the design’s promise.
Feedback and the time-box. Three presets, no slider. The duration picker offers 30 minutes, 2 hours, or until tomorrow. The shelf shows the paused state with a countdown; a snackbar confirms when listening history resumes. The control is time-boxed only, not a permanent toggle. Permanent pause was ruled out because the ML signal would degrade. The cost: a user who really wants to opt out has to re-pause periodically, or use Settings · Privacy.
Persona impact. Parent is the primary beneficiary: Pause protects recommendations during somebody else’s listening session. Melodic Melanie is positive on the social case. Ranger Dave is positive on shared devices when his son’s music threatens to take over the shelf.